One of the results of the increase in everyday mobility and urban sprawl is that individuals are having to travel through spaces whose geography they are not necessarily familiar with. Also, driving assistance devices based on geolocation and navigation have proliferated over a number of years.
Like satellite guidance systems, these devices enable the individuals in cars, on a motorbike, on a scooter or on foot to move around with full knowledge of where they are located, and knowing what path to take to get from one point to another. The individuals are thus no longer lost and can even optimize their journey by having themselves guided over routes that are faster, less costly, or include services such as a gas station or a hospital.
The best known and most widely used guidance systems are the satellite guidance systems that use information transmitted by a satellite geolocation system, or GPS (Global Positioning System), which currently offers an accuracy of 15 to 100 meters for the mass market systems and requires the use of a GPS chip which has the drawback of having a high consumption of electrical energy to receive the signals from the satellites. Also, before starting, it is usually necessary to wait for the GPS to find the initial position and compute the route, which may take a few minutes. Furthermore, this type of system is not well suited to vehicles such as bicycles or scooters, which can take small paths not referenced on the maps of such systems.
There are also location systems that use global system for mobile communication, or GSM, has allowed the expansion of cell phone guidance services. The accuracy of positioning by GSM can range from 200 meters to several kilometers, depending on the type of place where the user is located, for example in an urban environment where the density of antennas is high, or in a rural environment where the density of antennas is low. The GSM method most commonly used is the one based on the cell identifiers, or cell ID, representative of the antennas. This method entails recovering the identifiers of the GSM antennas to which the terminal is connected. A database then establishes the link between the identifiers of the cells and the geographic positions of the antennas, and the mobile terminal is capable of estimating its position. The major drawbacks to this solution are the lack of accuracy and the need for a network connection to recover the information from the cells, which consumes electrical energy. Similarly, location by WIFI is possible but presents drawbacks similar to guidance by GSM; they also suffer from as yet incomplete coverage.
It is also known practice to use the radio frequency identification, or RFID, technology, can be used for geolocation inside buildings. A series of RFID tag readers equipped with different types of antennas are positioned in such a way as to cover all the desired area. This area is then subdivided into portions whose area varies according to the number of readers deployed and their power. When a person equipped with an active RFID tag is located in a part of the area, the system is capable of computing his or her position based on the number of readers which detect the RFID tag by referring to the pre-established subdivision scheme. In real time, this technique is relatively approximate and its accuracy primarily makes it possible to determine the room or the corridor in which the geolocated person is located. A major drawback with this solution is the need to deploy the RFID tags over all the places where the users are to be located.
Other systems, as illustrated in the French patent application FR 05 13269 are based on the use of inertial units which comprise sensors of accelerometer, gyroscope and magnetometer types. By merging data from these sensors, these systems estimate the orientation in three dimensions of the inertial unit. However, the measurements made by an inertial unit exhibit a significant time drift.
All these systems are high consumers of electrical energy, which is not compatible with use for biomechanically-driven vehicles, which have little or nothing in the way of energy reserves. Furthermore, some of these systems, dependent on a communication system, can also afford traceability of the individuals without their knowledge.
The present invention aims to overcome the problems cited above.